unsigned
tree_num_loop_insns (struct loop *loop)
{
basic_block *body = get_loop_body (loop);
block_stmt_iterator bsi;
unsigned size = 1, i;
for (i = 0; i < loop->num_nodes; i++)
for (bsi = bsi_start (body[i]); !bsi_end_p (bsi); bsi_next (&bsi))
size += estimate_num_insns (bsi_stmt (bsi));
free (body);
return size;
}
unsigned
tree_num_loop_insns (struct loop *loop, eni_weights *weights)
{
basic_block *body = get_loop_body (loop);
gimple_stmt_iterator gsi;
unsigned size = 0, i;
for (i = 0; i < loop->num_nodes; i++)
for (gsi = gsi_start_bb (body[i]); !gsi_end_p (gsi); gsi_next (&gsi))
size += estimate_num_insns (gsi_stmt (gsi), weights);
free (body);
return size;
}
void
flow_loop_dump (const struct loop *loop, FILE *file,
void (*loop_dump_aux) (const struct loop *, FILE *, int),
int verbose)
{
basic_block *bbs;
unsigned i;
if (! loop || ! loop->header)
return;
fprintf (file, ";;\n;; Loop %d:%s\n", loop->num,
loop->invalid ? " invalid" : "");
fprintf (file, ";; header %d, latch %d, pre-header %d\n",
loop->header->index, loop->latch->index,
loop->pre_header ? loop->pre_header->index : -1);
fprintf (file, ";; depth %d, level %d, outer %ld\n",
loop->depth, loop->level,
(long) (loop->outer ? loop->outer->num : -1));
if (loop->pre_header_edges)
flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
loop->num_pre_header_edges, file);
flow_edge_list_print (";; entry edges", loop->entry_edges,
loop->num_entries, file);
fprintf (file, ";; nodes:");
bbs = get_loop_body (loop);
for (i = 0; i < loop->num_nodes; i++)
fprintf (file, " %d", bbs[i]->index);
free (bbs);
fprintf (file, "\n");
flow_edge_list_print (";; exit edges", loop->exit_edges,
loop->num_exits, file);
if (loop_dump_aux)
loop_dump_aux (loop, file, verbose);
}
/* Cancels the LOOP; it must be innermost one. */
void
cancel_loop (struct loops *loops, struct loop *loop)
{
basic_block *bbs;
unsigned i;
if (loop->inner)
abort ();
/* Move blocks up one level (they should be removed as soon as possible). */
bbs = get_loop_body (loop);
for (i = 0; i < loop->num_nodes; i++)
bbs[i]->loop_father = loop->outer;
/* Remove the loop from structure. */
flow_loop_tree_node_remove (loop);
/* Remove loop from loops array. */
loops->parray[loop->num] = NULL;
/* Free loop data. */
flow_loop_free (loop);
}
static bool
tree_estimate_loop_size (struct loop *loop, edge exit, edge edge_to_cancel, struct loop_size *size,
int upper_bound)
{
basic_block *body = get_loop_body (loop);
gimple_stmt_iterator gsi;
unsigned int i;
bool after_exit;
vec<basic_block> path = get_loop_hot_path (loop);
size->overall = 0;
size->eliminated_by_peeling = 0;
size->last_iteration = 0;
size->last_iteration_eliminated_by_peeling = 0;
size->num_pure_calls_on_hot_path = 0;
size->num_non_pure_calls_on_hot_path = 0;
size->non_call_stmts_on_hot_path = 0;
size->num_branches_on_hot_path = 0;
size->constant_iv = 0;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Estimating sizes for loop %i\n", loop->num);
for (i = 0; i < loop->num_nodes; i++)
{
if (edge_to_cancel && body[i] != edge_to_cancel->src
&& dominated_by_p (CDI_DOMINATORS, body[i], edge_to_cancel->src))
after_exit = true;
else
after_exit = false;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " BB: %i, after_exit: %i\n", body[i]->index, after_exit);
for (gsi = gsi_start_bb (body[i]); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple *stmt = gsi_stmt (gsi);
int num = estimate_num_insns (stmt, &eni_size_weights);
bool likely_eliminated = false;
bool likely_eliminated_last = false;
bool likely_eliminated_peeled = false;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, " size: %3i ", num);
print_gimple_stmt (dump_file, gsi_stmt (gsi), 0, 0);
}
/* Look for reasons why we might optimize this stmt away. */
if (gimple_has_side_effects (stmt))
;
/* Exit conditional. */
else if (exit && body[i] == exit->src
&& stmt == last_stmt (exit->src))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " Exit condition will be eliminated "
"in peeled copies.\n");
likely_eliminated_peeled = true;
}
else if (edge_to_cancel && body[i] == edge_to_cancel->src
&& stmt == last_stmt (edge_to_cancel->src))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " Exit condition will be eliminated "
"in last copy.\n");
likely_eliminated_last = true;
}
/* Sets of IV variables */
else if (gimple_code (stmt) == GIMPLE_ASSIGN
&& constant_after_peeling (gimple_assign_lhs (stmt), stmt, loop))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " Induction variable computation will"
" be folded away.\n");
likely_eliminated = true;
}
/* Assignments of IV variables. */
else if (gimple_code (stmt) == GIMPLE_ASSIGN
&& TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
&& constant_after_peeling (gimple_assign_rhs1 (stmt), stmt, loop)
&& (gimple_assign_rhs_class (stmt) != GIMPLE_BINARY_RHS
|| constant_after_peeling (gimple_assign_rhs2 (stmt),
stmt, loop)))
{
size->constant_iv = true;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " Constant expression will be folded away.\n");
likely_eliminated = true;
}
/* Conditionals. */
else if ((gimple_code (stmt) == GIMPLE_COND
&& constant_after_peeling (gimple_cond_lhs (stmt), stmt, loop)
&& constant_after_peeling (gimple_cond_rhs (stmt), stmt, loop)
/* We don't simplify all constant compares so make sure
they are not both constant already. See PR70288. */
&& (! is_gimple_min_invariant (gimple_cond_lhs (stmt))
|| ! is_gimple_min_invariant (gimple_cond_rhs (stmt))))
|| (gimple_code (stmt) == GIMPLE_SWITCH
&& constant_after_peeling (gimple_switch_index (
as_a <gswitch *> (stmt)),
stmt, loop)
&& ! is_gimple_min_invariant (gimple_switch_index (
as_a <gswitch *> (stmt)))))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " Constant conditional.\n");
likely_eliminated = true;
}
size->overall += num;
if (likely_eliminated || likely_eliminated_peeled)
size->eliminated_by_peeling += num;
if (!after_exit)
{
size->last_iteration += num;
if (likely_eliminated || likely_eliminated_last)
size->last_iteration_eliminated_by_peeling += num;
}
if ((size->overall * 3 / 2 - size->eliminated_by_peeling
- size->last_iteration_eliminated_by_peeling) > upper_bound)
{
free (body);
path.release ();
return true;
}
}
}
while (path.length ())
{
basic_block bb = path.pop ();
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple *stmt = gsi_stmt (gsi);
if (gimple_code (stmt) == GIMPLE_CALL)
{
int flags = gimple_call_flags (stmt);
tree decl = gimple_call_fndecl (stmt);
if (decl && DECL_IS_BUILTIN (decl)
&& is_inexpensive_builtin (decl))
;
else if (flags & (ECF_PURE | ECF_CONST))
size->num_pure_calls_on_hot_path++;
else
size->num_non_pure_calls_on_hot_path++;
size->num_branches_on_hot_path ++;
}
else if (gimple_code (stmt) != GIMPLE_CALL
&& gimple_code (stmt) != GIMPLE_DEBUG)
size->non_call_stmts_on_hot_path++;
if (((gimple_code (stmt) == GIMPLE_COND
&& (!constant_after_peeling (gimple_cond_lhs (stmt), stmt, loop)
|| constant_after_peeling (gimple_cond_rhs (stmt), stmt, loop)))
|| (gimple_code (stmt) == GIMPLE_SWITCH
&& !constant_after_peeling (gimple_switch_index (
as_a <gswitch *> (stmt)),
stmt, loop)))
&& (!exit || bb != exit->src))
size->num_branches_on_hot_path++;
}
}
path.release ();
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "size: %i-%i, last_iteration: %i-%i\n", size->overall,
size->eliminated_by_peeling, size->last_iteration,
size->last_iteration_eliminated_by_peeling);
free (body);
return false;
}
/* Checks that LOOPS are all right:
-- sizes of loops are all right
-- results of get_loop_body really belong to the loop
-- loop header have just single entry edge and single latch edge
-- loop latches have only single successor that is header of their loop
-- irreducible loops are correctly marked
*/
void
verify_loop_structure (struct loops *loops)
{
unsigned *sizes, i, j;
sbitmap irreds;
basic_block *bbs, bb;
struct loop *loop;
int err = 0;
edge e;
/* Check sizes. */
sizes = xcalloc (loops->num, sizeof (int));
sizes[0] = 2;
FOR_EACH_BB (bb)
for (loop = bb->loop_father; loop; loop = loop->outer)
sizes[loop->num]++;
for (i = 0; i < loops->num; i++)
{
if (!loops->parray[i])
continue;
if (loops->parray[i]->num_nodes != sizes[i])
{
error ("Size of loop %d should be %d, not %d.",
i, sizes[i], loops->parray[i]->num_nodes);
err = 1;
}
}
free (sizes);
/* Check get_loop_body. */
for (i = 1; i < loops->num; i++)
{
loop = loops->parray[i];
if (!loop)
continue;
bbs = get_loop_body (loop);
for (j = 0; j < loop->num_nodes; j++)
if (!flow_bb_inside_loop_p (loop, bbs[j]))
{
error ("Bb %d do not belong to loop %d.",
bbs[j]->index, i);
err = 1;
}
free (bbs);
}
/* Check headers and latches. */
for (i = 1; i < loops->num; i++)
{
loop = loops->parray[i];
if (!loop)
continue;
if ((loops->state & LOOPS_HAVE_PREHEADERS)
&& (!loop->header->pred->pred_next
|| loop->header->pred->pred_next->pred_next))
{
error ("Loop %d's header does not have exactly 2 entries.", i);
err = 1;
}
if (loops->state & LOOPS_HAVE_SIMPLE_LATCHES)
{
if (!loop->latch->succ
|| loop->latch->succ->succ_next)
{
error ("Loop %d's latch does not have exactly 1 successor.", i);
err = 1;
}
if (loop->latch->succ->dest != loop->header)
{
error ("Loop %d's latch does not have header as successor.", i);
err = 1;
}
if (loop->latch->loop_father != loop)
{
error ("Loop %d's latch does not belong directly to it.", i);
err = 1;
}
}
if (loop->header->loop_father != loop)
{
error ("Loop %d's header does not belong directly to it.", i);
err = 1;
}
if ((loops->state & LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
&& (loop_latch_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP))
{
error ("Loop %d's latch is marked as part of irreducible region.", i);
err = 1;
}
}
/* Check irreducible loops. */
if (loops->state & LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
{
/* Record old info. */
irreds = sbitmap_alloc (last_basic_block);
FOR_EACH_BB (bb)
{
if (bb->flags & BB_IRREDUCIBLE_LOOP)
SET_BIT (irreds, bb->index);
else
RESET_BIT (irreds, bb->index);
for (e = bb->succ; e; e = e->succ_next)
if (e->flags & EDGE_IRREDUCIBLE_LOOP)
e->flags |= EDGE_ALL_FLAGS + 1;
}
/* Recount it. */
mark_irreducible_loops (loops);
/* Compare. */
FOR_EACH_BB (bb)
{
if ((bb->flags & BB_IRREDUCIBLE_LOOP)
&& !TEST_BIT (irreds, bb->index))
{
error ("Basic block %d should be marked irreducible.", bb->index);
err = 1;
}
else if (!(bb->flags & BB_IRREDUCIBLE_LOOP)
&& TEST_BIT (irreds, bb->index))
{
error ("Basic block %d should not be marked irreducible.", bb->index);
err = 1;
}
for (e = bb->succ; e; e = e->succ_next)
{
if ((e->flags & EDGE_IRREDUCIBLE_LOOP)
&& !(e->flags & (EDGE_ALL_FLAGS + 1)))
{
error ("Edge from %d to %d should be marked irreducible.",
e->src->index, e->dest->index);
err = 1;
}
else if (!(e->flags & EDGE_IRREDUCIBLE_LOOP)
&& (e->flags & (EDGE_ALL_FLAGS + 1)))
{
error ("Edge from %d to %d should not be marked irreducible.",
e->src->index, e->dest->index);
err = 1;
}
e->flags &= ~(EDGE_ALL_FLAGS + 1);
}
}
free (irreds);
}
/* Unswitch single LOOP. COND_CHECKED holds list of conditions we already
unswitched on and are therefore known to be true in this LOOP. NUM is
number of unswitchings done; do not allow it to grow too much, it is too
easy to create example on that the code would grow exponentially.
Returns true LOOP was unswitched. */
static bool
unswitch_single_loop (struct loop *loop, rtx cond_checked, int num)
{
basic_block *bbs;
struct loop *nloop;
unsigned i;
rtx cond, rcond = NULL_RTX, conds, rconds, acond, cinsn;
int repeat;
edge e;
HOST_WIDE_INT iterations;
/* Do not unswitch too much. */
if (num > PARAM_VALUE (PARAM_MAX_UNSWITCH_LEVEL))
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching anymore, hit max level\n");
return false;
}
/* Only unswitch innermost loops. */
if (loop->inner)
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching, not innermost loop\n");
return false;
}
/* We must be able to duplicate loop body. */
if (!can_duplicate_loop_p (loop))
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching, can't duplicate loop\n");
return false;
}
/* The loop should not be too large, to limit code growth. */
if (num_loop_insns (loop) > PARAM_VALUE (PARAM_MAX_UNSWITCH_INSNS))
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching, loop too big\n");
return false;
}
/* Do not unswitch in cold areas. */
if (optimize_loop_for_size_p (loop))
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching, not hot area\n");
return false;
}
/* Nor if the loop usually does not roll. */
iterations = estimated_loop_iterations_int (loop);
if (iterations >= 0 && iterations <= 1)
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching, loop iterations < 1\n");
return false;
}
do
{
repeat = 0;
cinsn = NULL_RTX;
/* Find a bb to unswitch on. */
bbs = get_loop_body (loop);
iv_analysis_loop_init (loop);
for (i = 0; i < loop->num_nodes; i++)
if ((cond = may_unswitch_on (bbs[i], loop, &cinsn)))
break;
if (i == loop->num_nodes)
{
free (bbs);
return false;
}
if (cond != const0_rtx
&& cond != const_true_rtx)
{
rcond = reversed_condition (cond);
if (rcond)
rcond = canon_condition (rcond);
/* Check whether the result can be predicted. */
for (acond = cond_checked; acond; acond = XEXP (acond, 1))
simplify_using_condition (XEXP (acond, 0), &cond, NULL);
}
if (cond == const_true_rtx)
{
/* Remove false path. */
e = FALLTHRU_EDGE (bbs[i]);
remove_path (e);
free (bbs);
repeat = 1;
}
else if (cond == const0_rtx)
{
/* Remove true path. */
e = BRANCH_EDGE (bbs[i]);
remove_path (e);
free (bbs);
repeat = 1;
}
} while (repeat);
/* We found the condition we can unswitch on. */
conds = alloc_EXPR_LIST (0, cond, cond_checked);
if (rcond)
rconds = alloc_EXPR_LIST (0, rcond, cond_checked);
else
rconds = cond_checked;
if (dump_file)
fprintf (dump_file, ";; Unswitching loop\n");
/* Unswitch the loop on this condition. */
nloop = unswitch_loop (loop, bbs[i], copy_rtx_if_shared (cond), cinsn);
gcc_assert (nloop);
/* Invoke itself on modified loops. */
unswitch_single_loop (nloop, rconds, num + 1);
unswitch_single_loop (loop, conds, num + 1);
free_EXPR_LIST_node (conds);
if (rcond)
free_EXPR_LIST_node (rconds);
free (bbs);
return true;
}
static bool
doloop_valid_p (struct loop *loop, struct niter_desc *desc)
{
basic_block *body = get_loop_body (loop), bb;
rtx insn;
unsigned i;
bool result = true;
/* Check for loops that may not terminate under special conditions. */
if (!desc->simple_p
|| desc->assumptions
|| desc->infinite)
{
/* There are some cases that would require a special attention.
For example if the comparison is LEU and the comparison value
is UINT_MAX then the loop will not terminate. Similarly, if the
comparison code is GEU and the comparison value is 0, the
loop will not terminate.
If the absolute increment is not 1, the loop can be infinite
even with LTU/GTU, e.g. for (i = 3; i > 0; i -= 2)
APPLE LOCAL begin lno
Note that with LE and GE, the loop behavior is undefined
(C++ standard section 5 clause 5) if an overflow occurs, say
between INT_MAX and INT_MAX + 1. We thus don't have to worry
about these two cases.
APPLE LOCAL end lno
??? We could compute these conditions at run-time and have a
additional jump around the loop to ensure an infinite loop.
However, it is very unlikely that this is the intended
behavior of the loop and checking for these rare boundary
conditions would pessimize all other code.
If the loop is executed only a few times an extra check to
restart the loop could use up most of the benefits of using a
count register loop. Note however, that normally, this
restart branch would never execute, so it could be predicted
well by the CPU. We should generate the pessimistic code by
default, and have an option, e.g. -funsafe-loops that would
enable count-register loops in this case. */
if (dump_file)
fprintf (dump_file, "Doloop: Possible infinite iteration case.\n");
result = false;
goto cleanup;
}
for (i = 0; i < loop->num_nodes; i++)
{
bb = body[i];
for (insn = BB_HEAD (bb);
insn != NEXT_INSN (BB_END (bb));
insn = NEXT_INSN (insn))
{
/* A called function may clobber any special registers required for
low-overhead looping. */
if (CALL_P (insn))
{
if (dump_file)
fprintf (dump_file, "Doloop: Function call in loop.\n");
result = false;
goto cleanup;
}
/* Some targets (eg, PPC) use the count register for branch on table
instructions. ??? This should be a target specific check. */
if (JUMP_P (insn)
&& (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
|| GET_CODE (PATTERN (insn)) == ADDR_VEC))
{
if (dump_file)
fprintf (dump_file, "Doloop: Computed branch in the loop.\n");
result = false;
goto cleanup;
}
}
}
result = true;
cleanup:
free (body);
return result;
}
